38 Antarctic Dry Valleys:
1. The Antarctic environment and the Antarctic Dry Valleys.
2. Cold-based glaciers and their contrast with wet-based glaciers.
3. Microclimate zones in the Antarctic Dry Valleys (ADV) and their
implications.
4. Landforms on Earth and Mars: A comparative analysis of analogs.
5. Biological activity in cold-polar deserts.
6. Problems in Antarctic Geoscience and their application to Mars.
The Dry Valleys: A Hyper-Arid Cold Polar Desert
Temperate Wet-Based Glaciers
Cold-Based Glaciers
Antarctic Dry Valleys:
Morphological Zonation,
Variable Geomorphic Processes,
and Implications for
Assessing Climate Change on Mars
Antarctic Dry Valleys
•
4000 km2; Mountain topography
– (2800 m relief).
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•
•
Coldest, driest desert on Earth.
Mean annual temperature: -20o C.
Mean annual snowfall (CWV):
– Min. = <0.6 cm; Max. = 10 cm.
– Fate of snow: Sublimate or melt.
•
A hyperarid cold polar desert.
•
Topography controls katabatic wind flow:
– Funneled through valleys, warmed by adiabatic compression.
– Enhances surface temperatures, increases sublimation rates of ice and snow.
•
•
•
Bedrock topography governs local distribution of snow and ice:
Biology sparse: ~1 mm “Antarctic mite”; microscopic nematodes.
Environment very useful for understanding Mars climate change.
Antarctic Dry Valleys
•
4000 km2; Mountain topography
– (2800 m relief).
•
•
•
Coldest and driest desert on Earth.
Mean annual temperature: -20o C.
Mean annual snowfall (CWV):
– Minimum = <0.6 cm; Maximum = 10 cm.
– Fate of snow: Sublimate or melt.
•
Generally a hyperarid cold polar desert.
•
Topography controls katabatic wind flow:
– Funneled through valleys, warmed by adiabatic compression.
– Enhance surface temperatures, increase sublimation rates of ice and snow.
•
•
•
Bedrock topography governs local distribution of snow and ice:
Biology sparse: ~1 mm-sized “Antarctic mite”; microscopic nematodes.
Environment very useful for understanding Mars climate change.
Antarctic Dry Valleys
•
•
Hyperarid cold polar desert.
But, significant variations
within this climate.
•
These variations involve small but important differences:
– Annual surface temperature (meltwater).
– Relative humidity.
– Soil moisture (and type of subsurface ice).
We have defined three different microclimate zones within the
Antarctic Dry Valleys.
These are useful for understanding Mars climate change.
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•
Microclimate Zones
Upland frozen zone Inland mixed zone
Coastal thaw zone
Distribution of surface meltwater
No traditional “active layer”
No seregation ice
Regions with soil moisture < 3%
Discontinuous A. L.
Ice and sand wedges
Soil moisture variable
Dynamic Active Layer with
segregation ice and wedges
Soil moisture ~ 30 to > 50%
< -30 C to -35 C
Upland Frozen Zone
-20 C to -27 C
Inland Mixed Zone
Origins of subsurface ice?
-14 C
Coastal Zone
Distribution of surface meltwater
No traditional active layer
No segregation ice
soil moisture <3%
-8°C (<-30 C)
Upland frozen zone
Discontinuous A. L.
sand wedges
Soil moisture
variable
-4°C (-22 C)
Dynamic active layer with
segregation ice and wedges
Soil moisture ~30 to >50%
-2°C (-14°C)
Inland mixed zone Coastal thaw zone
POLYGONS
Upland frozen zone
Inland mixed zone
Sublimation
Sand-wedge
Coastal thaw zone
Ice wedge
A. J. Johnsson and E. M. Kakkinen, Earth Sciences Centre, Gothenburg Sweden
Viscous-flow features
Upland frozen zone
Inland mixed zone
Coastal thaw zone
Solifluction lobes
Debris-covered glaciers
Gelifluction lobes
Applications to Mars
Debris covered glaciers as analogs for viscous flow
features on interior of Crater walls
Crater wall
248 W/ 36 S M04/02881
161 E / 78 S
Crater wall
247 W / 38 S M18/00898
Mullins
Debris-Covered Glacier,
Beacon Valley, Antarctica
Origin of debris-covered glaciers in upland zone
Protective lag of sublimation till
Fate of debris-covered glacier ice?
Sublimation Polygons
POLYGON AGE: in-situ ashfall
LU1017/EMS 98 13A/pkt. W
Grains
Ar40/Ar39
Ar38/Ar39
1
12.839
0.01792
1
9.972
0.01284
1
11.385
0.01565
2
9.148
0.02338
2
13.401
0.01518
2
10.557
0.01518
J = 0.00049301
Ar37/Ar39
Ar36/Ar39
0.0373
0.01448
0.0325
0.00422
0.0565
0.00996
0.0433
0.00152
0.0410
0.01518
0.3368
0.00626
Ar39 (moles)
3.11E-16
2.89E-16
2.99E-16
5.21E-16
3.03E-16
4.56E-16
% Ar40*
66.55
87.35
74.03
94.93
66.41
82.56
Ar40*/Ar39K
8.545
8.711
8.429
8.685
8.900
8.719
Age (Ma)
7.58
7.73
7.48
7.71
7.90
7.74
7.69
Error (Ma)
0.08
0.08
0.07
0.08
0.08
0.06
0.10
Applications to Mars
Sublimation polygons as an analog
for basketball-textured terrain on Mars
A. J. Johnsson and E. M. Kakkinen, Earth Sciences Centre, Gothenburg Sweden
Applications to Mars
Debris covered glaciers as analogs for viscous flow
features on interior of Crater walls
Crater wall
248 W/ 36 S M04/02881
161 E / 78 S
Crater wall
247 W / 38 S M18/00898
OBLIQUITY
VARIATIONS AND
CLIMATE CHANGE ON
MARS
History of Climate Change of Mars:
Superposed Geomorphological Climate Indicators
Rock Weathering In Antarctica and Mars
Antarctica
Antarctica
Mars
Mars
Key Issues in Antarctic Dry Valley Geoscience
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Age of landscapes, surfaces and weathering rates.
Modes of rock weathering and soil formation.
Stability of microclimate zones; effects of global warming.
Debris-covered alpine glaciers: Formation and evolution.
Sublimation till: Modes of formation and evolution.
Role of sublimation till in inhibiting vapor diffusion, ice loss.
Age of ancient ice in subsurface: Oldest ice on Earth?
Analysis of ancient climate record in buried ice.
Polygon origin and evolution.
Implications for Antarctic and global climate change.
Provide clues to map changing climate on Mars.
Exobiological studies on Earth, application to Mars.
Sampling for life detection in extreme
environments: Antarctic Dry Valleys
• Buried ice ancient microbial communities:
– Paul Falkowski and Kay Bidle, Rutgers.
• Lipid biomarkers and isotopic ratios from soil profiles:
– Yongsong Huang, Brown University.
• Amino Acid Racemization (AAR):
– Alexander Tsapin (JPL)
• Molecular biological and Limulus Amebocyte Lyste
(LAL) Analyses:
– Rebecca Gast, WHOI.
• Ribosomal RNA:
– Linda Amaral Zettler, MBL.
The Dry Valleys: A Hyper-Arid Cold Polar Desert